what is the differents between the number of electrons in selenium and the number of electrons in aluminum ?

Chemistry

2 answers:

uysha [10]3 years ago

8 0

Answer:

The number of protons in the nucleus of the atom is equal to the atomic number (Z). The number of electrons in a neutral atom is equal to the number of protons. The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus.

Ulleksa [173]3 years ago

4 0

I hope this can help ;)

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What is the molarity of a solution in which 7.1 g of sodium sulfate is dissolved in enough water to make 100. mL of solution?

Sidana [21]

Answer:

0.50 M

Explanation:

Given data

Mass of sodium sulfate (solute): 7.1 g

Volume of solution: 100 mL

Step 1: Calculate the moles of the solute

The molar mass of sodium sulfate is 142.04 g/mol. The moles corresponding to 7.1 grams of sodium sulfate are:

$7.1g \times \frac{1mol}{142.02g} = 0.050mol$

Step 2: Convert the volume of solution to liters

We will use the relation 1 L = 1000 mL.

$100mL \times \frac{1L}{1000mL} =0.100L$

Step 3: Calculate the molarity of the solution

$M = \frac{moles\ of\ solute }{liters\ of\ solution} = \frac{0.050mol}{0.100L} =0.50 M$

3 0

3 years ago

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Place the following solutions in order of increasing osmotic pressure. I. 0.15 M C2H6O2. II. 0.15 M MgCl2, III. 0.15 M NaCl, A.

lozanna [386]

Answer:

D. I < III < II

Explanation:

The osmotic pressure (π) is given by the relation:

π = iMRT.

where, π is the osmotic pressure.

i is van 't Hoff factor.

M is the molarity of the solution.

R is the general gas constant.

T is the temperature.

M, R and T are constant for all solutions.

So, the osmotic pressure depends on the van 't Hoff factor.

The van 't Hoff factor is the ratio between the actual concentration of particles produced when the substance is dissolved and the concentration of a substance as calculated from its mass.